The disclosed embodiments relate to a magnetic resonance scanner, a magnetic resonance imaging system with a magnetic resonance scanner, and a method for operating a magnetic resonance imaging system with a magnetic resonance scanner.
Magnetic resonance (MR) imaging is a widespread method for obtaining images of the interior of a body. The body to be examined is exposed to a relatively strong main magnetic field, e.g., a strength of several tesla. A radio frequency (RF) excitation signal (the so-called B1 field) is then emitted using a suitable antenna system. The excitation signal tilts the nuclear spins of atoms resonantly excited by the RF field through a particular flip angle relative to the magnetic field lines of the main magnetic field. The RF signal radiated during the relaxation of the nuclear spins, the so-called magnetic resonance signal, is then picked up in suitable antenna systems. The antenna system may also be the same as the transmission antenna system. The raw data acquired is used to reconstruct the desired image data. For spatial encoding, defined magnetic field gradients are respectively superposed on the main magnetic field via gradient coils during the transmission and readout, or reception, of the RF signals. The resulting rapidly switched fields and currents lead to an interaction with the main magnetic field, metallic components of the MR system, or both the main magnetic field and the metallic components. As a result, disturbing vibrations may occur in the MR system that are detrimental to the imaging.
Different types of antenna systems may be used for the transmission and readout, respectively. For example, so-called local coils may be placed on the patient. The local coils may be connected via a suspension system to parts of the magnetic resonance imaging system, such as the patient couch. The local coils may be arranged at a maximum distance of a few centimeters from the patient.
Magnetic resonance imaging systems usually have antenna systems located at a somewhat larger distance from the patient, e.g., a few tens of centimeters. This antenna system may be a so-called body coil. Typically, the antenna elements of the body coil are constructed on a support tube that cylindrically encloses a measurement space of the magnetic resonance imaging system (the so-called patient tunnel).
If the antenna systems are mechanically coupled to parts of the magnetic resonance imaging system, the antenna systems are excited in typical oscillations during operation of the magnetic resonance imaging system by the vibrations that occur during operation. These oscillations are perceptible in various ways. On the one hand, the oscillations may influence the quality of the imaging, or the SAR exposure of the patient. On the other hand, the antenna systems set in oscillation also emit sound that may be unpleasant to a patient.